Production characteristics of oil-in-water emulsions using microchannel homogenisation

Microchannel homogenisation (MCH) is a highly efficient technique for producing uniform emulsions in a one-pass process. This involves passing premix emulsions through a microchannel (MC) array chip. The preparation of oil-in-water (O/W) emulsions using MCH has not been thoroughly explored compared to other premix emulsification methods. Therefore, in the present work, we aimed to clarify the production characteristics and productivity of O/W emulsions in a one-pass process using MCH with an asymmetric straight-through MC array. Numerous asymmetric straight-through MCs, each comprising a microslot and circular microhole (diameter: 10 mm), were microfabricated on a silicon-on-insulator chip. The continuous phase was a Milli-Q water solution containing 9.0% (w/w) polyethylene glycol and 1.0% (w/w) polyoxyethylene 20 sorbitan monolaurate. The dispersed phase comprised 10 - 30% (v/v) soybean oil or medium-chain triacylglycerol oil. The volume mean diameter (d4,3) of the O/W emulsions prepared via MCH was approximately 15 mm below the critical pressure. Emulsion fluxes reached > 1.0 m3/(m2 h) even with 30% (v/v) dispersed phase. These results demonstrated that MCH with an asymmetric MC array could stably prepare O/W emulsions with a high dispersed-phase concentration in a one-pass process. Furthermore, MCH achieved high throughput, comparable to that of premix membrane emulsification.